It is well known that the presence of foreign solid matter within an individual's vascular system can have serious adverse effects on an individual's health, either directly or indirectly. Such solid matter most commonly takes either the form of a thrombus, i.e., gelatinous, free-floating matter within a vascular channel but not adhered to the channel itself, or atheroma, which is most commonly a buildup of plaque or the like on the wall of a vessel. A wide variety of techniques are known for removing or breaking down such matter within the vascular system. Some techniques, known as thrombolytic therapy, utilize pharmaceutical compounds, e.g., urokinase, or streptokinase, to help dissolve such foreign matter.
Other techniques take a mechanical approach and attempt to dislodge the solid matter from the walls of the vascular system, if necessary, and then remove the solid matter from the vascular system by means of suction or the like. In dislodging plaque from vascular walls, an elongate wire with one or more scraping blades adjacent the distal end is rotated within the vascular channel. By moving the rotating blades axially into contact with the plaque, the blades will tend to dislodge it, permitting the dislodged particulate matter to be withdrawn from the vascular system by means of suction through a catheter or the like. A similar technique may also be used to break a relatively large thrombus into a number of smaller pieces which may then be extracted by aspiration.
This prior art technique does have a number of significant disadvantages, though. First, the rotating blades, which commonly rotate at between about 2,000 and about 35,000 rpm, are exposed, therefore posing a significant risk of puncturing the wall of an artery or a vein. It is estimated that this occurs in up to one-third of the procedures carried out with such a rotating blade, posing serious health risks each time such a device is used.
Another disadvantage of this procedure is that it is unable to finely grind the particulate matter; it simply tends to dislodge relatively large pieces of the built up plaque or break a large thrombus into a small number of individual pieces which remain fairly large themselves. Because this free-floating solid matter would tend to form additional thrombi if permitted to remain in the vascular system, they must be removed. As noted above, this is most commonly done by attempting to draw the thrombi out of the body through a catheter under suction. In so withdrawing the thrombi, one must necessarily withdraw a significant amount of blood as well. The volume of blood withdrawn from the patient must obviously be replaced, so additional blood supplies must be available for transfusion into the patient undergoing this procedure.
Accordingly, it would be desirable to provide a means of reliably breaking down a thrombus or the like sufficiently to permit the resulting small particles to be left within the vascular system without any significant disadvantage. Additionally, it would be useful to provide such a medical device which would be centered within a vascular channel and spaced away from the vascular walls to minimize trauma to the lumen of the vessel and the risk of puncturing the vessel wall.